WASHINGTON -LRB- CNN -RRB- -- The world 's tropical forests are disappearing , and one reason is simple economics : People , companies and governments earn more by logging , mining or farming places such as the Amazon jungle than by conserving them .

Global climate change treaty , scheduled for completion in December , is designed to protect tropical forests .

Efforts to halt rain forest destruction date back decades , but they so far have failed to tackle the issue on a scale commensurate with the challenge .

Now there may be a remedy , and the reason is climate change . Increased awareness of the threat from global warming has prompted unprecedented international focus on how to combat it , as well as new appreciation for the vital role of tropical forests in the climate change equation .

On Tuesday , world leaders gather at the United Nations for a special climate change summit , intended to build momentum for a new global climate change treaty being negotiated by almost 200 countries . The new treaty is scheduled to be completed in December in Copenhagen , Denmark .

If eventually enacted , the treaty will include a revolutionary but little-known provision intended to protect remaining tropical forests .

Known as Reduced Emissions from Deforestation and Degradation in developing countries , or REDD , the provision is based on the knowledge that destroying tropical forests contributes to global warming .

Rain forests absorb and store huge amounts of carbon dioxide , the most prevalent of the greenhouse gases that cause climate change . Burning or clearing the forests returns that stored CO2 to the atmosphere , where it can trap heat and gradually increase temperatures .

Every year , tropical forests equal to an area the size of England are destroyed , contributing about 20 percent of total annual greenhouse gas emissions -- more than all the world 's cars , trucks and airplanes combined .

The idea of the proposed provision is to make the stored carbon dioxide in the forests a commodity that can be bought and sold on the global market .

Polluters in the developing world would be able to offset their emissions by buying credits for stored forest carbon dioxide . The money from those purchases would go to developing world governments , international organizations , local communities and others involved in forest protection programs .

For the first time , tropical forests would be worth money for simply existing . That could create an economic incentive to protect tropical forests , which also have biological value as the planet 's richest storehouses of land species and spiritual worth as pristine natural landscapes .

To longtime defenders of tropical forests , the proposal represents the final stage of a long and halting journey from the fringes of the environmental movement toward the mainstream of international policy .

`` Done properly , this is our No. 1 hope , '' said Randall Hayes , who founded the Rainforest Action Network in 1985 with the goal of halting tropical deforestation . `` Other strategies have been heroic but insufficient . ''

The system would let nations and industries that are the biggest greenhouse-gas emitters buy carbon credits in tropical forests in South and Central America , Africa , Southeast Asia and other equatorial regions . At the same time , investors could speculate on the price of carbon dioxide through credit trading . Private and public funds could invest in projects that protect forests to generate credits .

Final details of the plan remain uncertain , such as how forest carbon credits would be verified and how the money paid for them would be handled and distributed .

For developing countries , the idea represents a potential new revenue source . President Bharrat Jagdeo of Guyana , a leading proponent of the plan , has made trading carbon credits a central element of his Low-Carbon Development Strategy .

The strategy `` is more about development than about the environment and it will help us to accelerate infrastructural development and fill the budget gap , '' Jagdeo said in an August 29 speech .

The World Bank and partners have set up funds to help developing countries prepare for REDD and finance forest-protection initiatives . However , both funds are not fully capitalized , pending the successful conclusion of negotiations on the new global climate change treaty .

`` Right now everybody is in a wait-and-see mode , '' said Benoit Bosquet , the World Bank 's lead carbon finance specialist . `` Everybody seems interested , but the level of activity is still humble . ''

Conservationists cite the environmental benefits of saving tropical forests , which provide essential resources and services -- such as fresh water , food , flood control and many others -- on which more than a billion people depend . Now , they say , conserving forests also can contribute to sustainable development , benefiting both nature and people .

Yet several steps remain before the tropical-forest provision becomes reality on a large scale .

First , the U.N.-led negotiations must agree on a treaty to succeed the Kyoto Protocol -- the world 's first global climate change agreement , which expires in 2012 .

The Kyoto treaty created a global carbon market -- but only the carbon storage of newly planted or replanted forests is eligible for credits . REDD also would protect standing forests , to prevent the absorbed carbon dioxide stocks from being released back into the atmosphere .

Whether a new treaty will be completed in December is unclear . Negotiators have yet to set consensus targets for reducing greenhouse gas emissions , and major disputes remain between industrialized powers such as the United States and emerging and developing economies including China and Brazil .

The draft under negotiation includes REDD , but negotiations continue on how broad the policy would be .

Advocates of a limited scope for REDD say areas with no history of deforestation should be excluded because protecting them wo n't reduce carbon dioxide emissions .

In response , conservationists and developing nations warn against leaving out nations and regions -- including Jagdeo 's Guyana , parts of Indonesia and Brazil , Democratic Republic of Congo and others -- that still have much of their tropical forest intact .

They argue that halting deforestation in only some countries would cause the loggers , palm oil developers and other drivers of forest destruction to move to previously untargeted areas .

`` If REDD mechanisms exclude any significant group of countries , REDD will fail , '' Jagdeo told U.N. negotiators in December .

Critics , including some environmental groups , question how such a vast and complex system can be successfully implemented .

A Greenpeace report issued in March said including REDD credits in carbon markets would create a glut and drastically cut the price of carbon , resulting in industrial polluters buying cheap credits for offsets instead of reducing their emissions .

The report also warned of reduced investments in renewable energy technologies due to the lack of an incentive from the cheaper carbon credits .

Others question whether REDD will be another scheme generated by industrialized nations to exploit resources of the developing world , and in particular , the indigenous forest peoples .

Jagdeo , the president of Guyana , has said such critics should recognize the opportunity that a new climate change treaty could present . If it includes sufficiently robust commitments for reducing greenhouse gas emissions , he argues , that would create a strong demand for carbon credits .

The deforestation provision of a climate change treaty could help stem deforestation while providing `` badly needed capital flows to some of the poorest countries in the world , '' he said .

Yet even the idea 's most ardent supporters recognize that it could take years for a global-scale program to become effective .

While local projects exist in rain forest countries such as Madagascar , it would take time and money to expand them .

`` If there is a deal in Copenhagen and if there is a signaling by industrialized nations that , yes , they will make money available , then you will see developing countries scaling up their readiness , '' said the World Bank 's Bosquet . `` They will see that this is now real and it 's the time to react . ''

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World leaders gather at the United Nations for special climate change summit

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Treaty based on finding that destroying tropical forests adds to global warming

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With proposed provision , stored carbon dioxide in forests could be bought and sold

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Reduced Emissions from Deforestation and Degradation provision has critics